Charge Tranfer

Discussion in 'Physics' started by Jake1234, Oct 14, 2007.

  1. Jake1234

    Thread Starter Member

    Oct 14, 2007
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    This may seem stupid, but I don't understand why a glass rod attracts a block of wax when the glass rod is rubbed with silk and the wax rubbed with wool. I understand that when the wool rubs the wax, electrons from the wool transfer to the wax making the wool positively charged and the wax negatively charge. This makes the rubbed wool attracted to the wax, but repelled by the silk. However, is it the other way around with silk and glass. When the silk rubs the glass, do electrons from the glass transfer to the silk, making the glass attracted to the wax because the glass would be positively charged and the silk negatively charged? I just need some clarification on this.
     
  2. Mike M.

    Active Member

    Oct 9, 2007
    104
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    That makes abosolutely no logical sense and is a very intersting argument, provided all the facts are true. The only question I see can be asked is, "does the wool repel the silk without first coming into electrical contact with it, direct or indirect?". If the silk become less negative by rubbing glass than the wool becomes positive and an electrical connection through your body or directly is made, the positive from the wool may fill in the negative of the silk, and then some to balance charge, both of which become positive. Or, if the silk becomes more negative by rubbing the glass than the wool becomes positive by rubbing the wax and a connection is made, the negative of the silk may fill in the positive of the wool, and then some to balance charge, both of which become negative.

    The question of whether the rod comes into contact with the wax before attraction doesn't make sense because they would have the options of neutral/neutral, positive/positive, or negative/negative if a charge balance occured. Since they attract, it can clearly bee seen that an electrical balance hasn't been established.
     
  3. Jake1234

    Thread Starter Member

    Oct 14, 2007
    19
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    Here are the facts:

    1. When a wool cloth is rubbed on wax, the wax is attracted to the wool.
    2. When silk is rubbed on glass, the glass attracts to the silk
    3. When two rubbed silk clothes or two rubbed wool clothes are brought together they repel.
    4. When two rubbed wax blocks or two rubbed glass rods are brought together they repel.
    5. When a wax block and a glass rod are brought together, they attract.
    6. When the wax block is brought close to the rubbed wool and rubbed silk, the block exhibits a weak attraction to the wool and a weak repulsion to the silk.

    Using these facts and thinking through them logically, the rubbed wax must have an excess of electrons from the wool when rubbed by the wool meaning the wax is negatively charged. The wool will have an electron deficit, meaning a positive charge. Unlike charges attract, like charges repel so the rubbed wool repelling the rubbed wool and attracting the wax block makes sense, justifying points 1, 3, and 4. When the glass rod is rubbed by the silk, the electrons from the glass rod are transfered to the silk, making an excess electron quantity on the silk (negatively charging it) and a deficit electron quantity on the glass rod (positively charging it). This accounts for points 2, 5 and 6 because the wax block would attract the glass rod because they have different charges, wax block positive and glass rod negative. I just wanted to make sure this was correct. I'm pretty sure it is.
     
  4. Mike M.

    Active Member

    Oct 9, 2007
    104
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    From your original post: wool and silk repel even though the silk is negative and the wool is positive as described in your second post. That doesn't make sense. Why would opposite charges repel?
     
  5. Jake1234

    Thread Starter Member

    Oct 14, 2007
    19
    0
    Sorry I wasn't very clear in the first post. I think I figured it out though and I explained it well enough in the second post. At least according to the text I used for school, the second post should be correct. The wool and silk will attract.
     
  6. Mike M.

    Active Member

    Oct 9, 2007
    104
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    OK. You really had me thinking hard because of that one mistake there. I was trying to imagine what could have led to the reversal of one of the items. That actually took more thought that the "half a camel" problem in the math forum on this site!
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Try a Google search on the phrase "Triboelectric series" :cool:
     
  8. Mike M.

    Active Member

    Oct 9, 2007
    104
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    Here is the most interesting application of electrostatics that I have ever seen. There are also videos on google video and hundreds of discussions all over the net.
     
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